I recently came up on some service docs and decided to write a guide on how to adjust a 3 wire TPS. This version of TPS is mostly found on automatics 95/96 and up. This process is different from earlier models where instead of measuring resistance (OHM) and continuity, voltage determines correct adjustment. In the interest of not breaking any copyrights regarding pictures, I have included my own diagrams, enjoy.

Tools needed Digital voltage meter - capable of measuring DC volts to the second decimal (1.00) most cheap voltage meters can do this. Feeler gauge - you need a 0.14"(3.5mm) gauge. Phillips screw driver number 2 preferably as you want to get a good grip on soft aluminum TPS screws.

Pre inspection 1. Inspect idle adjust screw cap and throttle arm screw for signs of tampering, any adjustment to these may damage ISC and make TPS adjustment impossible.2. Make sure the ISC plunger pushes forward when cold and key in on position.

Adjust 1.warm up vehicle to operating temperature.2.turn off3.remove air cleaner.4.set ignition to ON (engine not running)

5.WARNING! CRITICAL STEP. Check the ISC plunger has retracted and is not touching throttle arm. DO NOT MOVE PLUNGER BACK BY HAND, YOU CAN DAMAGE THE PRESSURE SENSOR INSIDE RENDERING YOUR ISC USELESS. If plunger is touching arm , warm up vehicle some more, if it just wont go back, make sure vehicle can reach operating temp (>195F) if it cannot get warmed up you may have a temperature sensor or thermostat problem. If temperature is ok and plunger will not retract, you may have an ISC problem.

6.place feeler gauge between idle adjust screw and throttle arm.7.probe center wire on TPS. Loosen screws and adjust so voltage is between 0.98vdc and 1.02vdc.8.tigthen screws. Probe again making sure readings did not change. Remove gauge and reinstall air cleaner.DONE!

Thanks el zilcho, nice work
but on my car it just doesn't seem to apply. Would love to get my hands on an original Suzuki copy of the procedure!

You say quote" you need a 0.14"(3.5mm) gauge" , but 0.14 inch is not 3.5mm or vice versa. 0.14'' maybe about 0.38mm. I tried using a 0,35mm guage, but it wont work because with hot engine, ignition on and with engine at halt, the ISC position is such that the gap is larger than 0.35mm. The gauge will thus "fall through". After starting the hot engine, the gap gets smaller at normal idling engine. It seems that with ignition on but without engine started, the ISC applies some "foot on the gas" to aid in starting.
On the other hand, 3.5mm (0.55 inches) seems a lot. Maybe you could check what size guage is OK. Perhaps someone has an original Suzuki copy of the procedure for adjusting the 3-wire TPS.

Mine is a Hungarian built 1996 MK3 1.0L with a 3-wire TPS, part no.: 132420-50G00.
Idle adjustment screw looks untampered. At idle or continuous 3000rpm all is 100% OK. On the highway it gets good mileage too, but in normal driving it runs too rich and the exhaust gets sooty. There are no error-codes, just code 12=OK. Just repaced the catalyst to get it through emission tests (passed!) and would prefer not having to replace the new one again! Looks like TPS adjusment may be out of spec. Thankful for any hints.

Thanks,
Helmut

Last edited by Helmut on Mon Dec 05, 2005 6:19 am, edited 1 time in total.

I have a 91 Firefly 3 cyl that I was having cold temp starting issues with and to make a long story short I changed the TPS and would like to adjust it to the right settings. I found this post but my problem is that mine does not have an ICS. So I need to know if the values would be the same as those listed above and if the entire process is the same or not.
Thanks
Arron

alright beave, there are 5-wire and three-wire TPS's out there. This thread is about the 3-wire, but most are for 5-wire. No doubt you will find what you need.

After getting the TPS back right, you may want to address the hard starting when cold issue. I would check everything to do with the ignition. Are the ignition cables good, and have they every been replaced? They deteriorate in time. Is their electrical resistance OK? Plugs good and gapped right? Another issue: Is the compression OK?

I have the cold start problem taken care of, water in the fuel. My question is about the 3 wire TPS that is on my car that does not have an ISC motor on it. I need to know if the adjustment procedure and the values aare the same as listed above.
Thanks

I tried this tonight at work and got funny results. The car now idles too high and has an annoying sloooowww return when you let off the gas. I drove it home just to see if it got any better or maybe was less jerky when letting off and hitting the pedal again... but sadly no change. It's not like I changed it much either! Only made about a .1v shift.

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